Aquatic Invasive Species Change Ecosystem Services from the World�s Largest Wild Sockeye Salmon Fisheries in Alaska

Abstract

This study combines a multi-method approach to structured expert judgment with market valuation to forecast fisheries damages from introduced invasive species. The method is applied to a case study of Alaska�s first submersed aquatic invasive plant, Elodea spp., threatening Alaska�s salmon fisheries. Assuming that Elodea spp. remains unmanaged, estimated mean damages to commercial sockeye fisheries aggregated across Alaska amount to a potential $159 million annually with a 5% chance of exceeding $577 million annually ($2015 USD). The associated mean loss of natural capital amounts to $5.1 billion cumulatively over the next 100 years reaching $400 million after 10 years. Results from the expert elicitation indicate that there is a 35% chance of positive net benefits associated with the believed positive effects of Elodea spp. on sockeye salmon (Oncorhynchus nerka). Despite the potential for positive net gains, the magnitude of the most probable damage estimate may justify substantial investment in keeping productive freshwater systems free of aquatic invasive species. The damage estimate for Alaska is significantly larger than similar estimates in the Great Lakes where ecosystems are already impaired by multiple aquatic invasive species, underscoring the value of keeping functioning ecosystems with global market value productive. This study is the first to estimate ecosystem service loss associated with introduction of an aquatic invasive species to freshwater habitat that supports the world�s most valuable wild sockeye salmon fisheries. Important policy implications related to natural resource management and efficient allocation of scarce resources are discussed